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                [Heoi2013]Alo                </h1>
                <p>时间限制：20s&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  空间限制：256MB</p>			</div>
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                                <h3>题目描述</h3><p><p><span style="font-size: medium">Welcome to ALO ( Arithmetic and Logistic Online)。这是一个VR MMORPG&nbsp;，<br />
如名字所见，到处充满了数学的谜题。<br />
现在你拥有n颗宝石，每颗宝石有一个能量密度，记为ai，这些宝石的能量<br />
密度两两不同。现在你可以选取连续的一些宝石（必须多于一个）进行融合，设为 &nbsp;ai, ai+1, &hellip;, a&nbsp;j，则融合而成的宝石的能量密度为这些宝石中能量密度的次大值<br />
与其他任意一颗宝石的能量密度按位异或的值，即，设该段宝石能量密度次大值<br />
为k，则生成的宝石的能量密度为max{k xor&nbsp;ap | ap &ne; k , i &le; p &le; j}。 <br />
现在你需要知道你怎么选取需要融合的宝石，才能使生成的宝石能量密度最大。 <br />
</span></p></p><hr/><h3>输入格式</h3><p><p><font size="4">第一行，一个整数&nbsp;n，表示宝石个数。&nbsp;<br />
第二行，&nbsp;n个整数，分别表示a1至an，表示每颗宝石的能量密度，保证对于i &ne; j有&nbsp;ai &ne; aj。&nbsp;<br />
&nbsp;<br />
</font></p></p><hr/><h3>输出格式</h3><p><p><font size="4">输出一行一个整数，表示最大能生成的宝石能量密度。 <br />
</font></p></p><hr/><h3>样例输入</h3><pre>5 
9  2 1 4 7
 
 
</pre><hr/><h3>样例输出</h3><pre>14 
 
 </pre><hr/><h3>提示</h3><p><p><br />
【样例解释】 <br />
选择区间[1,5]，最大值为 7 xor 9。 <br />
&nbsp;<br />
&nbsp;<br />
对于 100%的数据有 1 &le; n &le; 50000, 0 &le; ai &le; 10^9</p></p><hr/><h3>题目来源</h3><p>加强型数据By Hta</p>
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